This could be a placebo effect, but I used SetCPU and set up profiles for my RAZR and did notice an extension of battery life so far. But again, I think you would need to do individual testing here as I haven't been able to run a solid burn down on the battery life. If you do go this route, then I simply have two profiles, one of them being to set the CPU at 300mhz (I think it is) when the screen is off.